Small optoelectronic modules such as imaging devices and light projectors employ optical assemblies that include lenses or other optical elements stacked along the device's optical axis to achieve desired optical performance. In some applications, it is desirable for there to be a gap (e.g., air or vacuum) on one or both sides of some of the optical elements through which the device's optical path passes. The air (or vacuum) gaps can help ensure that the optical elements provide the desired optical effect on light signals as they pass through each optical element. The gaps also can help prevent chemical interactions between the optical elements and surrounding materials. Such chemical interactions may adversely impact the optical properties of the optical elements.
Manufacturing assemblies or modules with such gaps, however, is non-trivial. Among other things, in many applications, space is at a premium. Thus, it can be important to maintain a relatively small overall z-height for the module or optical assembly. Since the introduction of the air (or vacuum) gaps generally increases the overall height of the assembly or module, it would be desirable to provide techniques that allow the gaps to be made relatively thin.